The present invention relates to a loop substrate suitable for use with a hook-and-loop fastening system. The present invention also relates to an abrasive sheet material.
Abrasive sheet materials are widely used for a variety of applications and include, by way of illustration only, sandpapers, emery cloths, sanding discs for rotary sanders, and sanding strips for orbital and belt sanders. By utilizing very fine abrasive materials, abrasive sheet materials also can be used for polishing operations. Abrasive sheet materials most often comprise a layer of an abrasive, i.e., abrasive particles or grit, which is attached to a substrate or base of varying thickness and basis weight by means of an adhesive.
In some instances, the abrasive sheet material is used by itself or wrapped by hand around a block or pad. In other instances, the abrasive sheet material is attached at distal ends by mechanical means to a motorized sanding tool having a disc or pad. Because of the rapid movement of such a motorized sanding tool, the unattached edges of the abrasive sheet material are easily damaged or torn. It is, therefore, desirable that the abrasive sheet material is substantially completely attachable to the disc or pad of the sanding tool. For many applications, the abrasive sheet materials need to be readily exchanged for other sheets, either to replace worn-out sheets or to change to a finer or coarser grit.
Abrasive sheet materials which are substantially completely attachable to and readily removable from a sanding tool are known. In some embodiments, these materials are attached by a pressure-sensitive adhesive. In other embodiments, they include a looped fabric having a paper sheet attached to the back thereof by an adhesive. The free surface of the paper has an abrasive attached thereto by means of an adhesive. The looped fabric is attachable to a hook-type attachment means well known to those in the art.
Abrasive sheet materials based on a hook-and-loop attachment mechanism have several advantages over abrasive sheet materials which are attached to a sanding tool by means of a pressure-sensitive adhesive. For example, the former, unlike pressure-sensitive adhesive types, remain firmly attached even when heated or cooled excessively. In addition, they are easily and cleanly removed after use. However, because they are made from two separate layers which have been laminated together, they are costly to manufacture. Moreover, delamination can occur, particularly under conditions of high stress or temperature. Conditions of high stress also can result in unacceptable stretching of the loops in a loop material which is attached to a sanding tool by a hook-type attachment means. This can result in the separation of the sheet from the tool during use or prevent reattachment of the sheet after removal. In either case, the useful life of the sheet can be significantly reduced. Accordingly, there is a need for an improved loop material which will reduce or eliminate such problems, particularly for abrasive sheet materials to be used in high stress applications.